Crustacea

Crustacea is a large, diverse group of arthropods, including familiar animals such as crabs, lobsters, crayfish, shrimp, krill, and barnacles. The crustacean group can be treated as a subphylum under the clade Mandibulata.

Characteristics

Crustaceans possess two-parted limbs and a hard exoskeleton that must be moulted for the animal to grow. They have a segmented body, which may be tightly fused (as in crabs and lobsters) or may be divided into a head, thorax, and abdomen (as in krill).

Classification

Crustaceans are typically classified into various taxonomic groups based on their morphology and other characteristics. These groups include:

• Class Malacostraca, which includes crabs, lobsters, krill, and others.
• Class Branchiopoda, which includes brine shrimp and Daphnia.
• Class Copepoda, which includes small, often parasitic species.
• Class Ostracoda, which includes seed shrimp.
• Class Maxillopoda, which includes barnacles and others.

Ecology

Crustaceans play key roles in marine ecosystems, freshwater ecosystems, and some terrestrial ecosystems. They are often the dominant members of the zooplankton in the ocean, providing the primary food source for many larger animals. Some species are detritivores, feeding on dead organic material; others are predatory, and a small number are parasitic.

Human use

Many crustaceans are also of significant economic importance to humans, and are raised commercially or harvested from the wild. These include species such as crabs, lobsters, shrimp, and krill, which are harvested for food on a large scale.

See also

• Arthropod
• Marine biology
• Aquaculture

References

Crustacea Resources
Latest articles Most recent articles Ongoing trials	Wikipedia